The present invention relates to automatic identification equipment for identifying a transponder by transmitting and receiving signals between an interrogator and a plurality of transponders. More specifically, the present invention has a particular feature in a memory configuration for the transponder (IC card).
A conventional method of managing an access right to an IC card is disclosed in JP-A-7-44425. In this method, one authentication key is assigned to an entire card, such that a person who successfully obtains authentication is allowed to access an overall memory of the IC card.
When such a conventional access right management method is extended to an IC card which has a memory divided into a plurality of areas, an authentication key must be set to each area in order to manage the access right for each of the divided areas, and an interrogator desiring an access to such areas must perform authentication for each of areas with different authentication keys. In this case, as the memory is divided into a larger number of areas, the increased number of authentication keys must be stored, so that a larger storage region is required. This results in a reduction in a memory region available to the user.
Assume, for example, that it is desired to individually manage the access rights to a plurality of interrogators for each of plurality of records, into which a memory of an IC card is divided. If the number of authentication keys equal to the number of records is defined, a larger storage region is required for storing the authentication keys, while a memory region available to the user tends to be reduced.
The terminal types of interrogators are defined, and authentication keys are stored in accordance with the number of the terminal types. Each record has the number of access permission bits equal to the number of the terminal types, such that the bits are set on or off to specify the terminal type which is permitted to an access thereto.